Circuit breaker with lever type current connection



C. D. AINSWORTH ETAL Filed Dec. 7, 1948 CIRCUIT BREAKER WITH LEVER TYPECURRENT CONNECTION Dec. "l2, 1950 Patented Dec. 12, 1950 UNITED STATESiATENT QFFlCE CIRCUT BEEAKER WITH LEVER TYPE CURRENT CONNECTION 7, 1948,Serial No. 63,932

(Cl. 20G- 82) Application December 9 Claims. i

This invention relates in general to improvements in electric circuitbreakers, and more particularly to means for conducting currents ofrelatively large intensity from onev stationary terminal of the breakerto the movable contact of the .breaker associated therewith.

Heretofore, the performance of exible conductors for electricallyinterconnecting a station ary terminal and a relatively movable solidcon* ductor has often proven unsatisfactory, and their use for thispurspose tended to become more objectionable as the speed and frequencyof contact actuation increased.. Flexible conductors have a limitedexural life due to fatigue or oxidation, thus requiring replacements atregular intervals of time.

It is, therefore, desirable to provide circuit breakers that are calledupon to operate fren quently with solid interconnecting conductorsrather than flexible interconnecting conductors. An arrangement of thistype comprising a solid interconnecting conductor calls for spring meansfor establishing the requisite contact pressure between thisinterconnecting conductor and contact surfaces associated therewith. Inhigh speed circuit breakers of the gas blast type the light weightmovable Contact isy generally operated by a pneumatic motor having apiston which is moved to the contact open position thereof by gas underpressure, and which is returned to the contact closed position uponremoval of the gas pressure therefrom by spring action. The spring meansused to establish the requisite contact pressure :between the solidinterconnecting conductor and the contact surfaces associatedtherewithmay serve a dual function as claimed in this application by beingadapted in addition to move the piston of the pneumatic motor and themovable contact associated therewith from contact open position tocontact closed position.

It is therefore one of the objects of the present invention to provide anew and improved circuit breaker of the fluid blast type in which arigid conductor is used to interconnect a movable conductor and astationary terminal associated therewith.

Another object of the present invention is to provide a new and improvedcircuit breaker in which an element is used both to interconnect amovable contact and a stationary terminal element associated therewithand to transmit the requisite actuating force to the movable contact formovement thereof in one direction.

y A further object of the present invention is tc providea new andimproved circuit breaker in which a spring means requiring minimumamount of space is used to reset a pair of cooperating contacts andwherein the spring means has a smaller stroke than the movable contact.

A still further object of this invention is to provide a new andimproved circuit breaker in which a dual purpose spring means actuates a.movable contact and establishes contact pressure between a rigidelement and the movable contact and terminal element associatedtherewith.

Objects and advantages other than those above set forth will be apparentfrom the following description when read in connection with theaccompanying drawing in which:

Fig. 1 is a view in axial cross section, of an interrupting chamber of agas blast circuit breaker involving the present invention; and

Fig. 2 is a top view of the solid interconnecting conductor and theguiding surfaces associated therewith in the embodiment illustrated inFig. l.

Referring more particularly to the drawing by characters of reference,Fig. 1 illustrates an interrupting head l which comprises a flange orsupporting base member 2 which is clamped by means of cap screws 3 on acap (not shown) connecting the flange to a source or" arc extinguishingiiuid under pressure. Base member 2 supports a tubulaiinsulator l ofceramic or other suitable insulating material of which porcelain is anexample. A force is applied toV a continuous clamping ring E by a seriesof screws E secured to base member 2 and a component of this force istransmitted through a split ring l onto the porcelain insulator in adirection substantially perpendicular to a surface 8 of p0rcelaininsulator l to secure the porcelain insulator thereto. This clampingstructure mini mines bending moments and shear stresses in theporcelain.

A conductive annular member 9 made in two parts is mounted on andsupported by insulator il by means oi a continuous clamping ring it, asplit ring il and screws l2 in a manner similar to that used to secureinsulator l to base member 2. An insulating tube I3 mounted within andaxially aligned with insulator fi is rigidly supported bybase member 2through a pressure it and surrounds a downward extending cylindricalportion I5 of conductive annular member Q with a small clearance.Insulator tube it also surrounds a pair of cooperating arccontacts leand l? and cooperates withnconductive cylindrical member e to define anarcing chamber I8.

Contact I is a fixed contact shaped as a streamlined solid of revolutionand is bolted to a tubular portion 28 of base member 2 extending intoinsulating tube I3. Contact IS has an arcing tip I9 of refractoryconductive material in the form of a plug and is providedwith aplurality of grooves 29 extending radially from substantially the tip ofthe plug along the outer surfaces thereof. These grooves provide passageWays for a limited flow of fluid under pressure through the arcingcontacts during contact engagement thereof. The base of Contact I3comprises a plurality of iin-like appendages 2l adapted to form aplurality of air passages.

The cooperating movable contact l1 comprises an annular shaped arcingportion defining an oriiice 22 and adapted to partially surround the topportion of stationary contact i3 upon engagement therewith. Contact I1further comprises a sleeve portion 23 and forms therewith the piston ofa fluid motor. Sleeve 23 is adapted to slide within guiding surfaceswhich, in turn, constitute downward extension portions i5 and 32 of theconductive cylindrical member 9. The Vupward stroke of sleeve 23 islimited by abutmentv of an annular projection 23a thereorc against' aflange 25 backed by suitable shock absorbing material, The interior ofsleeve 23 is insulated by a suitable material and forms with hollowinsulator I3 the arcing chamber I3. Y

When the arcing contacts I9 and I'I are closed they substantially closeorifice 22 and'essentially divide arcing chamber I8 into an inletchamber 26 andan outlet, chamber 21. The inlet chamber 26 is generallydened by insulating tube I3 and the hollow upward extending portion 23of base member 2. The outlet chamber 21 is generally conductors 33.Thus, as piston 24 moves under the influence of air pressure, sleeve 23moves upward in the interrupting head I and interconnesting conductors33 follow the vertical movement thereof by a combined rolling and wipingaction over the two contacting surfaces 36 and 33 associated therewith.Pairs of ears 4I provided on member 9 adjacent the sliding surfaces 38guide each interconnecting conductor 33 and align these interconnectingconductors in radially extending directions from the annular groove onthe outer surface of sleeve 23. Interconnecting conductors 33 may beshaped in any one of a number of ways, however, the chosen configurationmust permit a freedom of movement over the supporting surfaces engagingtherewith. The operable interconnecting conductors illustrated in thedrawing are provided with convex end portions in engagement with thesupporting surfaces, whereby movement of interconnecting conduotors 33takes place with a minimum of friction.

The helical spring means 39 act upon interconnecting conductors orlevers 33 at points intermediate their ends to provide a sufficientamount of contact pressure between conductors and the Vcontact surfacesengaged therewith. However, these springs have a dual function andadditionally eiect resetting or reclosing of concontained within sleeve23 and extends upward i to a suitable outlet 29 extending between member9 and a concave baiiie or cover 39 secured Outlet chamber 21 contains anauxthereto. iliary arcing electrode 3|. This electrode, which is securedto cover 39 and in electrical contact with member 9, is'usually axiallyaligned with sleeve 23.

A plurality of rigid interconnecting conductors 33 electrically connectthe movable contact I1 to member 9, which is provided with a terminallug 34 and therefore constitutes a stationary ter- Vminal element. Basememberr2, which is electrically connected to the stationary contact I6,constitutes the second stationary terminal elementand is provided with asuitable terminal lug (not shown).

Each rigid interconnecting conductor 33 is in the form of a rockingVcontact lever which is in permanent contact Vwith the conductivecylindrical member 9 and sleeve 23 at allV times. Sleeve 23 may beprovided with a groove 35 having a concave cross section extendingaround the circumference thereof and forms a bearing sur- Yface3ii forengagement of one end of the interconnecting conductors 33. Theconductive annular member 9, in turn, may be provided with a concavecircular groove 31 having an annular supporting surface 32 adapted tohingedly support the other end of conductors 33. Levers 33 extend inradial directions from sleeve 23 and,

while resting on supporting surfaces 36 and 38,

make with the axis .of sleeve 23 an angle which Vvaries with thelongitudinal position of the sleeve. A plurality of .dual purpose springmeans 39, axially-'aligned .with a plurality of .dual purpose springmeans 33, axially aligned with a plurality of pins 40, provide asubstantially constant pressure between flanges 25 and interconnectingtact I1 upon the decrease of pressure in the inlet chamber 25 upstreamof movable contact I 1. The

helical springmeans 39 are disposed so as notY to increase the overalldimensions of the circuit breaker. The stroke or compression Vof springmeans 39 upon movement of Vthe movable contact I1 is smaller than thestroke of contact I1.

Base member 2 provides a connection between a reservoir (not shown)constituting a source of are extinguishing fluid under ypressure and theinlet portion 25 of the arcing chamber I8 for the purpose of directing ablast of arc extinguishing iiuid under pressure between the arcingcontacts and through the arcing chamber. The arc extinguishing iiuidunder pressure may be an inert gas such as nitrogen. but it will beassumed herein that the fluid is air Vunder pressure of the` order of200 or more pounds per square inch supplied to the reservoir by asuitable compressor (not shown) Fig. 2 illustrates more clearly one ofthe inter- 4 In operation, the-circuit breaker being closed as indicatedin Figgl, current flows through a stationary terminal element (notshown), base member 2, stationary Contact I6, movable contact I1, sleeve23 of piston 24, conductors 33, conductive annular member 9, andstationary terminal element 33. Opening of the circuit breaker isinitiated by applying a blast of air under pressure through base member2 and into insulating tube I3 and the inlet chamber 25. Air pressure isthereby applied to the annular surface of movable contact I1 of piston24. VPiston 24 accordingly lifts contact I1 against the action of thedual purpose springs 39. Y An arc is *thereby drawn between contacts I 5and l1 and at the same time an air Yblast is established Ifrom the inletchamber 25 through orifice 22, outlet chamber 21, and exhaust outlet 29.Movable contact The gap formed between the arcing contacts I6"lfascinantes and I1 is' then of' such a value as to provide the most'efcient v'arc extinguishing 'action of the air blast therethrough.

The air blast causes one rootof the arc to move from its initialposition on the annular surface of movable contact l'! surroundingvorifice 22 to the inner edge of orifice 22. The root of the arc on thestationary contact i6 moves from the point of arc initiation radiallyand in a downstream direction until it reaches the downstream end ofarcing tip i9. The arc also gradually lengthens as its roots aredisplaced and sweeps through orifice 22,'and through a series ofpositions until one'portion of the extended arc loop contacts theauxiliary electrode'l positioned within the arcing `chamber i8. The arcthen extends between arci'ngtip i9 and electrode 3|r and is readilyextinguished by the air blast. After the arc is extinguished thepressure ci the air blast is reduced and the dual purpose springs 39move piston 24 vbaclcto its original position and contacts IG andH'reengage for normal operation.

Although but one embodiment of the present invention has beenillustrated and described, it will be app-arent to those skilled in theart that various changes and modifications may be made therein withoutdepartingy from the spirit of the invention or from the scope of theappended claims.

It is claimed and desired to secure by Letters Patent:

1.'In a switching device, the combination of a pair of stationaryterminal elements, a stationary contact electrically connected tor'oneof sai-:l terminal elements, a movable contact adapted to cooperate withsaid stationary contact and to reciprocate between a pair 0f extremepositions, a substantially rigid lever resting upon and conductivelyinterconnecting said movable contact and the other of said terminalelements, and dual purpose spring means for establishing contactpressure between said lever and said movable contact and between saidlever and said other of said terminal elements and for moving saidmovable contact from one of said extreme positions to the other of saidextreme positions.

2. A circuit interrupter comprising a stationary contact, a movablecontact cooperating therewith and defining a first supporting surface, apneumatic motor for separating said movable contact i from saidstationary contact, said motor comprising a piston forming an integralpart of said movable contact, means for extinguishing the arc formedbetween said contacts upon separation thereof, a conducting lever inengagement at one end thereof with and supported by said firstsupporting surface, a stationary conducting element defining a secondsupporting surface for the other end of said lever, and common springmeans for resetting said piston from the contact open position to thecontact closed position thereof and for exerting contact pressurebetween said lever and said supporting surfaces,

3. A circuit interruptor comprising a stationary contact, a movablecontact cooperating therewith and deiining a iirst supporting surface, apneumatic motor for separating said movable contact from said stationarycontact, said motor comprising a piston forming an integral part of saidmovable contact, means for extinguishing the arc formed between saidcontacts upon separation thereof, a conducting lever in engagement atone end thereof with and supported by said rst supporting surface, astationary conducting element defining a second supporting surface forthe other endfof said conducting lever, a pair of earsron saidstationary element'adjac'ent said second supporting surface for guidingsaid lever, and'co'mmon spring means for resetting said piston from thecontact open position to the contact closed position thereof and forexerting contact pressure between said lever and said supportingsurfaces.'

4. In a switching device, the combination of a pair of stationaryterminal elements, a stationary contact associated with one of saidterminal elements, a cooperating movable contact in coaxial relationvwith said stationary contact, contact separating means for moving saidmovable contact in the direction of the common axis of said contacts, aplurality of conductive rocking levers arranged substantially radiallywith respect to said common axis for interconnecting said movi ablecontact and theother of said terminal elements, supporting meansintegral with said movable contact groo'ved to receive one end of saidrocking levers and adapted to permit wiping movement thereon of saidrocking levers-means integral with said other terminal element defininga supporting surface for the' other ends of said rocking levers, aplurality of stationary'supports for helical springs, and a pluralityofhelical springs each resting with one end thereof on one ofxsaidsupports and with the other end thereof on one of said rocking levers.

5. In a switching device, the combination of a pair of stationaryterminal elements, 'a stationary lcontact conductively connected to oneof said terminal elements, amlovable contact adapted to cooperate withsaid stationary contact, contact separating means, a plurality ofrocking levers for conductively interconnecting said movable contact andthe other of said terminal elements, means integral with said movablecontact grooved to receive and to support one end of said rocking leversand adapted to permit a wiping movement thereon, means integral withsaid other terminal defining a supporting surface for the other ends ofsaid rocking levers, and spring means acting upon said rocking leversto' produce a wiping action between said rocking levers and surfacescontacting therewith upon movement thereof and to reengage said contactsupon separation thereof.

6. In a switching device, the combination of a pair of stationaryterminal elements, a stationaryl contact conductively connected to oneof said terminal elements, a movable contact adapted to cooperate withsaid stationary contact, lever means resting upon and conductivelyinterconnecting said movable contact and the other of said terminalelements, a uid motor for separating said contacts, said motorcomprising a piston forming an integral part of said movable contact, aSource of supply of fluid under pressure, means for admitting fluidunder pressure from said source to said motor and adjacent said contactsto cause separation of said contacts and extinction of the arc drawntherebetween, and spring means acting upon said lever means to produce awiping action between said lever and surfaces contacting therewith andto reset said piston from. the contact open position to the contactclosed position.

7. in a switching device, the combination of a pair of stationaryterminal elements, a stationary contact conductively connected to one ofsaid terminal elements, a movable contact adapted to cooperate with saidstationary contaict, a. piston forming an integral part of said movableContact and defining an annular circular groove having a concave crosssection around the circumference nl said levers havingA curved ends ofwhich one Vend of said lever is supported by the annular circular grooveof said .piston and the other end of said lever is hingedly supported bythe supporting surface of said stationary element, a pneumatic Ameansfor actuating said piston for separating said contacts and extinguishingthe arc Vdrawn therebetween, and a plurality of helical springs arrangedgenerally parallel to the axis of said contacts and each acting upon oneof said levers' for resetting said piston from the contact open positionto the contact closed position.

8. A circuit interrupter comprising a stationary contact, a movableVcontact cooperating therewith land defining a first supporting surface,a pneu-v inatic motor for separating said movable contact from saidStatiOnarycOntaCt, said motor comprising a piston forming an integralpart of said movable contact, means 'for extinguishing the, are formedbetween saidlcontacts upon separation thereof a conducting lever inengagement at one Y Y end thereof with an supported by said first sup-1f...

porting surface, a stationary conducting element Vdefining a. secondsupporting surface for the other end of said lever, and common springmeans e for resetting said piston fro-m the contact open position to thecontact closed position thereof 8 Y and Vfor exerting contact pressurebetween said lever and said supporting surfaces, said `Spring meanshaving a Smaller stroke than the stroke of said movable contact.

9. In a switching'device, the combination of a pair of stationaryterminal elements, a stationary contact associated with one of saidterminal elements, a reciprocable movable contact adapted to cooperatewith said static-nary contact, a substantially rigid conductive rockinglever disposed transversely of the directions of movement of saidmovable contact with one end thereof resting on only said movablecontact and with' the opposite end thereof on only the other of saidterminal elements, a stationary support for a spring means, and a springmeans resting with one end thereof upon said support and With the otherend thereof acting on said rocking lever substantialiy in one of saiddirections of movement for establishing contact pressure' betweensaid'lever and said other of said terminal elements and for aidingmovement oi said movable Contact in said one of said directions.

CHESTER D. AINSWOR'IH. GUSTAV Ef. JANSSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNrrED STATES PATENTS Prince Apr. l5, 1941

